This chapter highlights damage accumulation and final failure in composite materials subjected to fatigue loading with various stress ratios. Composite materials play a crucial role in various industries due to their lightweight and high-strength properties. However, their performance under cyclic loading raises concerns about potential damage accumulation, material degradation over time, and eventual failure. To address these concerns, stress-to-life data (S-N) are provided through ASTM standard testing for each load magnitude that the part will be exposed to during service operation. This data is essential for analysts to estimate damage accumulation using Miner’s rule, aiding in predicting failure. Reduction in structural stiffness and strength is also discussed to assess damage growth and accumulation under cyclic loading of different magnitudes. Another alternative to damage accumulation applying the Miner’s rule is to utilize the fracture mechanics approach instead. The fracture mechanics approach assumes a small preexisting crack in the composite material that will grow during cyclic load leading to final failure. Analysts must realize that due to the anisotropic nature of composite materials, the prediction of final failure using the Miner’s rule methodology or fracture mechanics approach may introduce significant errors. Factors influencing fatigue life, damage accumulation and progression, including material composition, loading conditions, and environmental factors, must be considered when studying structural fatigue life. Furthermore, the accumulation of damage from a fracture mechanics perspective is investigated in this review. By utilizing Miner’s rule, the progression of damage in composite parts under cyclic loads can be estimated by using fatigue crack growth methodology. A better understanding of fatigue behavior in composites contributes to comprehending the mechanisms governing damage accumulation during fatigue loading. Insights from this study have implications for optimizing material design, predicting component lifetimes, and enhancing the overall reliability of structures in a fatigue-prone load environment.